I need some advice!
is it best to fix my mortgage ( ive been offered 3.99% for a 5 year fix, no fees)...
or, go on a tracker at 3.89%.

will rates rise soon?

I haven't got a clue!

3.99% for 5 years will give you good stability and you should pick that one over the 3.89% tracker - interest rates are only going to go up so you are pretty safe with taking the 'hit' of 0.10%.

Anthony
http://www.comparethemortgagemarket.com

As a quick reminder, a fixed rate mortgage is where the interest rate on your mortgage loan is fixed at a certain percentage for a period of time – two or five years, for example. The benefit is that you know exactly what your mortgage payment will be each month, regardless of any changes in the Bank of England interest rate. It’s useful when you want to be sure about your monthly budget, or want the security of knowing exactly what your mortgage outgoings will be each month.