Tyre changes are quite easy to do at home if you have the right tools.
A purpose-made bead breaker will get the tyre off the rim, and once the rubber is in the 'well' of the wheel, good quality tyre levers for about £10 a pair, and rim protectors for a fiver along with muscle power should get the tyre off the rim.
Plenty of lubricant is crucial to getting the new tyre on.
A thick, soapy solution of liquid hand-soap and water is good.
A bit of carpet is handy to protect the brake discs and your knees and access to a compressor (a garage forecourt is fine) to get the sidewalls to seat evenly on the rim. Don't forget to reset the pressure.