If I update it will I get my BTC back or is that gone now ?
Your coins will not be lost. The problem here is that your client is sending transaction that has high-s value and the network has stopped accepting them. Multibit Classic v5.17 fixed this issue and enforces the low-s value in transaction. Your transaction would then be able to get propagated and confirmed.
Check your fees, just in case.
Reset the blockchain once you have done upgrading.
Thanks alot - i've tried updating but its making me go for MultibitHD - so ill install that and reset the blockchain and move it all over.
Thanks for the help - hopefully its all good now
That might not work, I don't think you can import private keys from multibit classic into multibit HD.
You can download the latest classic from here.
https://multibit.org/releases/multibit-classic/multibit-classic-0.5.19/
Click reset blockchain and transactions afterwards and try sending with the highest possible fee if your wallet will let you.