Get someone in to do it, a £50.00 router will not be man enough for the job, and you need a JIG and the correct router bit. There is also a possibility that the corner will not be perfectly square, so the worktops may also need to be scribed to get a good fit and joint.
I am no expert just an enthusiastic DIYER, i am sure someone more knowledgeable than me can offer advice, but that is the situation i had in my kitchen with three worktops and i got a local chap to come and do it. Two joints, and scribe 2 of the three worktops due to the room not being square.
Looks good, much better than nasty metals strips.
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