The house is rcd protected but i need a light too. thats why i was thinking garage unit.
No pipes in there yet, thats the next step....
Well a double socket is only rated at a total of 20 amps so you cannot put those two items into it.
That depends on make and type. Looking at MK there standard double socket rated 26A but their RCD and Filter versions rated at just 13A so clearly there can be a problem with large appliances overloading a double socket.
Neither my washer or my tumble drier are on the limit 2.2 kW seems normal today which would mean just over 19 amp for the pair. So in real terms often it is OK to run both from a double socket. However with plug in items it is so easy to replace without considering if the new one will cause an over load.
I remember when looking for the last replacement tumble drier looking at one designed to run over night. Instead of 2 kW for 1 hour it used 300 W for up to 6 hours which was claimed saved power and better for the cloths. I have switched my tumble drier from 2 kW to 1 kW and it does not take twice as long so clearly saving power.
My old washer used less electrical power than the new one, the new one in order to comply with energy saving bands uses more electric power. The old one also used power from my gas supply by have a hot fill, it seems hot and cold fill has gone all are now cold fill only. Yes they may save energy but gas is so much cheaper than electric.
My very old twin tub was really efficient with both power and water wash day was really a wash day all cloths went into same water white first followed but colours then vie the mangle to the spin drier and then washing line under car port. Only in freezing conditions was there a problem. However the Last of Summer Wine days are over and having days of the week split into washing, blacking grate and washing step, etc. are over. Our devices save more and more labour at the cost of electric power.
So at the moment we have no idea of power requirement it's just a guess, we also have no idea of supply type, again just a guess, All we do know is the old Part P rules are still valid as Gwynedd is in Wales. So work outside is a special location so if he wants it all legal then he either pays the LABC £100 plus vat plus any testers they employ to test it or us a scheme member electrician to do the work.