I have a leak as per photo,can anyone advise what i need to get.

Looks like you need a new thermostat housing seal/gasket. You may get away with just that. If not you'll need a new housing.

Housing is solid aluminium (VW "improved" this on the Felicia with a lovely plastic one renowned for breaking up). So long as no bolts snap when you undo it or there's no burrs on the mating surfaces it will be fine. The proper gasket is about a £1 from dealers or Jorily posted. To go with that you just need some sort of jointing compound. I used hylomar but there's probably something better for the job around. While you're in there replace the thermostat for the hell of it, they're only a fiver.

Drain the system first by removing bottom radiator hose from radiator. Keep heater setting on full throughout. If coolant hasn't been changed in a while get the garden hose out and flush through the system well. Take hose off the thermostat and feed water through the radiator a while, then with the thermostat housing off carefully try to flush water through the engine block - use some rags to prevent water going everywhere. When done fill it up with the good stuff, g12+ coolant mixed 50/50 with deionised water is probably best. To bleed the system run the engine with the coolant cap off, drape a cloth over to prevent splashes onto paintwork.