Driving Bristol to Lake District

I'd pull up somewhere like Chester, rather than do the whole trip in a day - personally I think a week is a long time in the Lake District, so for me, one night on the road has little opportunity cost.

But it depends on your travelling style - we like to pull up at every ruined abbey and crumbling castle, and have the odd coffee in picturesque villages - however YMMV.

Perfectly doable.
From Bristol to the Lakes is, apart from the 1st 3-4 & last 15 or so miles, motorway all the way. Your friend's suggestion of the roads not being so great, has little point as to the journey, realistically. The roads are fine, but the traffic might not necessarily be!
It does depend what time of day you travel, as to how long it takes you, but assuming there are no incidents en-route, it can be done in around 4 & a bit hours.
The M6 Toll, again on what time you travel, can cut a good 30-40 minutes off the journey time. It costs a little more or less than a fiver, depending on what time you use it but still works out, by far, as the UK's cheapest toll-road.
There are several ways of doing the journey from Bristol, personally I'd head up the M5 then join the M6 (& M6 Toll) onward to Jct. 36 for S. Lakes, or 40 upwards to 44 for N.Lakes.
Tebay Services (M6), beyond 36 is a lovely location, the food is superb, it wins awards year after year & from there, it's close to wherever you're going.
Hope it goes well.

Many thanks for these very helpful replies. Two other questions if possible :

(1) is the M6 Toll required to be paid in advance on the internet, or is it by direct payment in cash at either end of the M6?
(2) I'm also now wondering myself whether a week is too long in the Lake District. We are happy to do some walking in the area but I'm wondering whether 3 complete days would be sufficient to enjoy the area, then move on?

I'm also now wondering myself whether a week is too long in the Lake District.

I guess it depends on what else you are doing, and where the trip ends.

Hadrian's Wall and Durham Cathedral are quite close by - even Yorkshires Dales NP and York itself.

We had three nights at the Ambleside YHA - lovely - but two full days felt okay for us (driving and strolling around).

There is loads to see and do in the lakes for a week, more so if you like walking so it depends on your interests the biggest issue is the weather if you have a week if bad weather then it could be too long. But you have Lancaster nearby which is worth day trip even Blackpool.

As for driving apart from traffic it is not a difficult drive, I would personally do it in a day, the toll you pay at the access point. Chester would be a nice place to stop but not on route and warrants more than a night stopover.

Really insightful comments from you all - many thanks. The more I think about it the more I think that we should take time to get there (even driving up through Wales or staying in somewhere like Chester for a few days) and perhaps only planning to be in the Lake District for a few days. Will investigate LP guides further!

Chester is a great Roman city and a lovely place to stay for a couple of days. It's only issue is there is not a lot of accommodation so best to book in advance as it can be quite expensive.

The M6 Toll, again on what time you travel, can cut a good 30-40 minutes off the journey time

Whilst the M5 up the west side of Birmingham is a piece of road I try hard to avoid, M6 toll isn't really in the right place for that purpose, as it by-passes the N side of Birmingham.

bjc- if you look at a road map you'll see the M6 toll is the other side of Birmingham, so you'd be doing 2 sides of a triangle to use it. Yes the M6 west of Birmingham does get extremely busy but time your arrival here for late morning and hope for the best. I would have no hesitation in planning to make this journey in one day, but like most of UK, if you want to divert off the motorway, there's something really interesting every 20 miles or so - Worcester, Ironbridge, the potteries if that is an interest around Stoke, Chester as already mentioned . . . .