Inflation rate is 2.4%, the lowest it has been for 2 years, down from a high of 5% at the end of 2011. With the BOE contemplating reducing the interest rate to 0.25%, it's worth considering fixing it for only 2 years.
Or if the reduction comes sooner, then go for a tracker. HSBC is doing a 2 year for 2.49% and the reverts to SVR after, which by that time may be very low.
With the economy and housing market in decline, together with low oil demand globally, I don't foresee the BOE raising the interest rate any time soon. There is plenty of spare capacity in the economy to cope with a sudden growth before generating any inflationary pressures.