All completely feasible.
Borrow against your main home to buy the second one, then pay off the mortgage when you eventually sell up and move to the second home permanently.
There'll be no CGT on your main home when you sell it because it's been (and will remain) your principle residence.
The only thing to concern yourself with is you'll have to pay additional 3% stamp duty on the second home, so that's something to budget for.
Thanks for that info. Appreciate it.
All looking positive at the moment. Will get financial advice once my mortgage is paid and I can then pursue this idea.