I concur, the Lettings Relief alone will cover any capital gain.
Sorry to be so long responding, I was out at the theatre for some culture.
I hope you do not mind me interjecting - I am also one of the UK tax experts here on Just Answer -
As private lettings relief is the lesser of
1) the amount of gain exempted for private residence relief
2) the gain left over after private residence relief has been applied OR
You will need to stay in this property for some time - as even a year living here (with no increase in your gain) you would only be due approx £7000 private residence relief (1/5th of the gain to represent living here for 1 year out of 5) and the same for private lettings relief, so a total of £14,000 from the gain of £35,000 still leaves £21,000 - and even after £11,100 annual exemption allowance (the new rate after 05/04/2014) you have a charge arising on the remaining gain of £9900 -
So its not correct you were advised that the private lettings relief would cover all of the gain - and I felt it was important to advise you of that position.