This might be a silly question but if I think my petrol is off do I need to drain the whole lot before putting in new or just the tank? There isn't much in it at all.

Would the carbs & plugs also need cleaned or is it worth a try just with new fuel?

Also what would I use for a spark plug wrench? Could I pick one up at Halfords or have to use a specific one?

You could try adding fresh fuel in the tank and drain the float bowls and see what comes out prior to an attempt to start it all depends on how long laid up and whether carbs were run dry or stale fuel has been left in there a while .
The plugs should be OK if running prior toolkit wrench saves a lot of hassle but a deep 13mm socket I think from memory fits but involves flaffing around getting the plugs in and out the deep recess David silver has the correct socket tool and Kayla on here sells the NLA from Honda handle if that helps .

holw old is old?

if its varnishy water skunk smelling fuel then get it out and disposed of.

if it doesnt smell like death and only a small amount in you could try just filling the tank with fresh fuel and burn it out that way.

if the fuel has been sitting a while it could have sludged up the carbs if they were not drained properly and they will need a strip and clean anyway so at the same time worth draining the tank.

Cheers for the help.

Added fresh fuel to the tank without draining as barely any in it, turned it over with kill switch off, fuel off to try clear the old fuel. Not sure if that actually works.

Everything back on and offered right away. Few attempts at bumping and getting closer and closer then finally.... It started and after a few splutters away I went. What a relief!