In reply to Jonathan J Higgins:
Consider the following for avoiding car hire:
* 55m flight to Glasgow, 3h45 train to Fort William
* 1h40m flight to Geneva, 1h bus transfer to Chamonix
The second option is slightly faster, though probably not in any meaningful way, as you're still looking a half day for travel. However, there's a big difference between being in FW with no car, and in Chamonix with no car. Honestly, unless you're meeting with someone else who can drive you, I don't think climbing in Scotland is really worthwhile/possible without a car. A place like Cham has the infrastructure in terms of buses, lifts, etc, but on the other hand you'll likely be paying more for accommodation and paying for the convenience of lifts as well.
If you're travelling to Europe, a flight and bus transfer can be all you need. However, please give consideration to whether that's justified for a short climbing trip. There are threads on here discussing how to do this via train as a greener alternative, though it seems apparently Eurostar still has some problems with ambiguity on check in and security restrictions.
If you're travelling to Scotland, I'd just drive. You need a car when you're up there anyway and a flight isn't going to save you much time with the airport travel and check in time. I shouldn't need to get into the discussion of whether it's green to use a plane to travel the length of England for a weekend away climbing. You could get a train and then hire a car, but unfortunately train prices have gone off the rails* and it's difficult to justify that price for the quality of travel experience (not to mention the probability of a delay).
* Yes! I did just say that!