SDLT on Leases Extension where Freehold held under Deed of Trust

[efreckel]

Hello

I own a flat in a block of three and, with the other leaseholders, we have purchased the freehold to our apartment block. This freehold is owned by us under a deed of trust with each shared of the freehold reflecting the underlying apportionment between the flats. We purchased the freehold in October 2016 for £40k and are now looking to extend our leases under a deed of variation. I'm a little unsure on the SDLT position, and I'm not sure if we need to worry about CGT as well, as all HMRC guidance I've been able to find is unclear (that's being polite).

Would I be correct to understand that, to the extent there is no consideration payable for the lease extension, there should not be any SDLT?

Any pointers on CGT, as it's related, would be gratefully received too!

Thanks