Welcome Dave
There are several basses in the £300 region which are worth looking at. The Marcus Miller Sire, The G&L Tributes, Squire Standard (both P and J pick ups) and Spector are all worth looking at. Avoid the Affinity range Fenders - all the above are better basses for the money.
Lots of bargains to be had in the Marketplace here so keep an eye on what's on offer.
Beware of the dreaded GAS - pointless telling you really as we all succumb to it.