Best Short term saving/investment option

Franko43

Need a little help here folks. Later this year I’m starting to build my own house, I’ve got a mortgage in place ready to go upon which they pay four 25% releases to me during the course of the self build. It will probably be September before I have to pay the builder any money and that will involve a £10K sum to bring me to sub floor level. Now currently DW and me have been saving really hard to hit this 10k (thus 10k less of a mortgage )) and we’ve hit the 7K mark. I have this money saved in my current account until such times as its released but I got to thinking that I should try and make this money work a little harder – the only problem being I will need access to it in about 3-6 mths time. Does anyone know of anywhere I could put it in between times that would make it work a little harder i.e. some sort of an account or investment that would not penalise me for an early withdrawal. Cheers all in advance