Deciding the way forward for my exit?

I am sure there are many here who will know more than me but I take it you have read through all this? https://www.lawcom.gov.uk/millions-of-leaseholders-to-benefit-from-law-commission-reforms/

How about looking into Rent to buy with your existing tenants.

Leasehold Reform will result in the biggest saving for those with the shortest lease term remaining so you might want to reconsider extending these until this new reform goes through albeit we don't know how long it will be before these go through. Could be another 1-3yrs.
Whether extending now or later, I don't know what Valuation & Legal Fees you're paying but Homehold charge a flat fee of £1950 + VAT for the legal side & valuation incl. negotiations. I deal with Linz Darlington Director (mobile whilst working remotely 07871 615 118). Go to their website; homehold.org

As Laura says, the pending changes to lease extensions should make a difference, if you can I'd hold off until then.
I don't know the purchase price to you, the rental or the sale price once extended, but it might be worth considering not extending at all and just to let them to the end of the lease, when you will be 99(ish).
It may make sense in terms of ease of life, if your purchase price, previous rental and 45 years potential rental balance or show profit.
Besides, who knows what further changes may occur, ( but that's a two edged sword).

Why sell any. What profit do you make now? Compare that to what you will make from three flats. With three flats you are more exposed to one void or one non paying tenant than with 10.
You will probably incur a CGT liability when you sell.

I think you are right to reduce your portfolio. Hundreds of new flats are going up everywhere, giving the remaining tenants market more choice and better negotiating position. Plus landlords legislation and taxes are much worse. And flat values will drop with so many competing to sell. A really bad combination. Family housing is in short supply so I'd keep yours if you can. Perhaps add another house or a large 3/4bed flat, valuable as a rarity. Tenant selection will be crucial for income reliability, but perhaps insurance might help there?

I agree about 3 properties not offering sufficient cover for voids and non-paying tenants. I did have plenty of cover with 2 London properties and 2 in Yorkshire. London did well for rental, non-voids and capital appreciation. Yorkshire has been a disaster for voids, damage, capital depreciation, etc... and now a non-paying tenant (9 months!!!) I can't move out. I've now realised my London profits but it has left me with a big problem in Yorkshire. The IO mortgage on one must be renewed in 3 years and the other in 6 years. Both in negative equity. Do I offload at a big loss? Sit and wait for leasehold reform and hopefully achieve RTE (we have RTM on both)? I'm 66. Do I really need the hassle?

I am in a similar position, age 60 and with 8 properties. One thing about selling and paying off the mortgage on 2 or 3 remaining properties is that, although the rental income overall is much reduced, the income reduction is not as bad as it may seem as of course there is no mortgage interest to pay, which in my case is about half the rental income. Another factor is that with fewer properties there are fewer costs and less likelihood of major works being needed, in other words, less risk.

Reply to the comment left by M&SFAN at 20/01/2021 - 11:23
Thanks for this. I need to research this more. I had heard something of this but thought the timeframe would be too shaky for me. I have seven years left on the mortgages of the flats on low leases and basically I think they are now worth (as a cash sale) what I owe on them. If I knew the timescale would be more reliable with the government making changes and the changes being substantial enough in my situation to be worth the wait then I would. The other issue I have is that these mortgages were sold onto Rosinca who do not allow further lending and quoted to me that they are not a mortgage company. Otherwise I could go to my mortgage company and apply for further borrowing to serve notice to extend the lease on all of the three remaining flats with low leases at once.

Reply to the comment left by Laura Delow at 20/01/2021 - 11:33
Thanks for this. How sure is it that these changes could become law within three years? The freeholder here is difficult so any loophole and he will start jumping. About ten years ago a group of the leaseholders got together to do a joint lease extension. The freeholders solicitor missed a crucial deadline and as a result the freeholder had to accept their first very low offer. Freeholder was furious and has hated the block ever since. The lease extension I have just done has taken over a year to do. With regards to fees I got a favor of £500.00 total to initially value all four flats at once. Then the fees for my valuer were £1000.00 plus vat on this one flat for the negotiations etc including serving notice for tribunal hearing that didn't proceed in the end. So I hope the negotiations would be easier next time round and as such the fees be a bit less. I need to understand the likely reduction in the cost of the lease extension and a better idea of the time frame of these proposed changes to convince me to put the brake on.