if the house has greatly appreciated in the 2 years , you can sell up now and owe no cgt on the gain. most people dont realise that for every year that you rent it out, a % of any gain (both present and future) becomes exposed to cgt.
i thought a lot about this issue myself and heres what i came up with.
VERY simple worst case scenario example
bought 1998 - 85000
current value (not budged in 2 years) 295000
sell now and pocket 210000 cgt free
just suppose market slows and the price or rental value didnt move for another 5 years and the house was let for this period.
this is the rough position
total years owned 11
cgt = 210000 / 11years *5 rented out *20% =
19,000
5 years rent @12,000 pa = 60,000
tax@42% (ignoring deductables interst/ins etc) = -25,200
rental "profit" = 34,800
subtract the cgt when you sell and you have 15,800 / 5 years = 3160 per year real profit
unless you were a millionaire, the 210000 would be borrowed to fund oyur new property
simple interest charged on this money @3.5% p/a = 7350
annual profit = minus 4190
if you think the value will go up significantly, it is another story
also , if you have little equity and a high mortgage, you should keep it as you have little to loose and any cgt/income tax liability will be based on future gains not whats already potentially there tax free.