Not only that, you are asking how long a piece of string is. You dont say:
What 'electrics' mean - are going to run a three phase lathe or just a light?
How far the garage is from the house,
What sort of consumer unit do you have (picture please)
Do you have a plan on where you would pick up the supply from
etc
etc
Per above, you wont get prices here, best to get a couple of quotes from local qualified sparks.
Dont forget that electrical works outside are notifiable. A qualified sparq will take away this pain.
If you want to do it yourself, please come back with more info and I'm sure you will get some constructive advice.
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