CGT - any ideas how much I'd owe??

[24again]

I'm getting a little bit stressed about this, any help would be very much appreciated.
House was bought in 2001 for £86,000. Think it's now worth £170,000. Moved in June last year and it's been rented out since. How much capital gains tax would we have to pay if we couldn't sell it before the new 18 month deadline. (DH higher rate tax payer - I don't pay tax)
Please help me work this out as I keep coming up with scary figures!

I think it is only payable on the difference between June 2013 and when you sell and even then you (each if jointly owned) have annual allowances to offset against the gain before tax applies. So potentially he would only pay on half the net gain.

Gain only counts from when it ceased to become your home

so value at last June (around £168000 guess)
then count gain from that (around £5000 by time of sale)
half each (around £2500 each)
less £10,000 CGT allowance each (equals nil)
remainder at 28% (equals nil)

equals not very much