WTD/Tacho regs - van and HGV

I’m currently driving an artic pulling a survey trailer (sorry if you’ve got caught behind me :blush: ). I’m working 5 days, nothing complicated, no problems with all the usual WTD stuff. However, over the festive period, this vehicle is being taken off the road for 3 weeks. As I am on a temporary contract, they don’t have to find me any other work during this time, but, they are talking about offering me an alternative position during this time.

Now, this would be driving a survey van, and their normal working pattern is 7 days on, 7 days off, working 10 hours a day, so averaging only 35hrs a week. My queries are as follows:

Can I drive 7 consecutive shifts when in a van? (Wednesday to Wednesday)

They class their survey drivers as ‘field based’, and do not pay for the time it takes you to get from wherever your shift ends, back home, regardless of how far away you are. Granted, you are away all week, and so only travel in and back once a week, but usually to and from a different area - there is no ‘base’ as such. The homeward journey may consist of dropping off a colleague to their home en-route, in a company vehicle. So do different rules apply when in a vehicle not covered by the tacho rules and regulations?

Could I legally do other HGV work on some of the 7 days off? (bearing in mind it could fall mid-week to mid-week)

I assume that if I do any HGV driving during the working part of the week, I would be bound by the driving regs for the remainder of the week with respect to working hours and rest periods? But is that in a fixed week, or between two weekly rest periods?

I thought I knew about WTD etc until this came along!

Anyone venture an opinion?