We live in Bucks and went City > Florence last year but it's a long way to City.
This year seven of us went LHR > Pisa. We were going to hire a couple of cars* in Italy anyway so just drove up. Little roads N of Florence, Fiesole etc can be a bit of a PITA as can Florence with roadworks confounding GPS plans; fined last year for inadvertently entering bus lane.
If we lived in London or to the east LCY would be great.
Anyway, on the return PSA>LHR they ran out of everything but snacks. I hope their stock planning is a bit better now.
* Hired from Avis via BA and all went well with not a single problem. In fact, I didn't accept GPS and took TomTom but the cars were fitted with SatNav anyway.