We are based near Stonehenge , just literally a minute of the A303If you're heading to the south then forum trade regulars @Absolut5 and @BognorMotors are in range.
And absolutely nothing bad about doing your research but deciding it's out of your comfort zone. Your more informed about what you want and what your needs are.
I have a rule of thumb at 30A - circuits above that I'm likely to ask someone who works with that sort of stuff everyday to do the work, if for no other reason they'll have better pro grade tools.
This type of install/upgrade is something we do on a weekly basis .