It does seem that it has been your main residence. It would have been preferrable to have nominated it as a main residence within the 2 years time limit to put the issue beyond any doubt. In the absence of an election, the issue is decided on the actual facts of each case.
If we accept that it has been your main residence as a matter of fact, you could let it if you wish for at least 3 years, probably more, and still not be liable for any CGT. This is because final 3 years ownership of a property used as an only or main residence is exempted and you also get lettings relief of upto £40,000 to set off against any chargeable gains in respect of lettings etc exceeding 3 years.
So, you don't have to sell because of CGT.
Ramnik
ramnikrp@hotmail.com