To cut mitred joins in laminate worktop you will need - A worktop Jig, a router fitted with a 30 mm collet and 12 mm cutter (see list below), and at least 2 clamps. A large square is also recommended.
A reasonable quote to fit a worktop would be £70 for the first cut and £20 for each additional cut. A typical L shaped kitchen with a sink and hob would cost £190 + VAT. If you purchased the tools at the lower end of the price range you could fit the worktop, have change from £190 and keep the tools!
Of course, you may find a fitter willing to fit your worktop for less than the above price.