i have done the UK run a few times i either go across to germany and then down or just stick to the french autoroute.... i do the german route more often as i sit around 160kmh, sayes me a bit of time, and no pissing about with the toll booths and questions from the Douane/ Gendarmarie.
both routes come into Basel where the swiss will happily relieve you of 40chf for a vignette, unless you come off 1 junction before and go thru a non motorway border ( st.louis in FR or weil am rhein DE ) and then scoot straight back on 5 mins later at the next junction.
a note to remember if you come on the autobahn, very close to the basel border you may see a huge line of trucks on the autobahn, stick to the far LH lane and go past them, they are waiting for customs clearance,
DO NOT sit in the Q behind them as a lot of foreign cars do. Weil exit is just past the last truck BTW! and you are visiting your mate in Basel if u get stopped at the regional border, unlikely as there are hundreds of UK cars here.
in CH highway speeds around 130 is fine, in tunnels/50/80?100 zones there will be cameras and they are not bright orange! but wouldnt worry about it as nothing will come thru the post.