It's worth bearing in mind many, if not most, Economics courses require A-level or AS level Maths. There are some that don't of course, but this will considerably limit your options. Additionally, Maths is probably the most valuable subject for any STEM subject at university, including biosciences and chemistry. It would be advisable to take this even if you were intending to pursue these subjects with full enthusiasm.
In any case, STEM roles vary considerably depending on exactly what area you go into. Most engineering positions are office based, for example, including (Bio)Chemical Engineering, Bio(medical) Engineering, or Materials Science. The combination of Maths/Chem/Bio would be suitable for a number of these courses, although inevitably they will involve some lab work to gather the data you need to analyse.
Additionally I don't know where you think labs are located - they don't put them in the middle of the fens (technically I suppose you could argue all of Cambridge falls into this category, and it is a major hub for biotech and computing firms, but it is a city nonetheless) and lone islands in the North Sea (sure oil rigs are out there, but Oil & Gas Engineers aren't going to work on a rig full time - they may occasionally do a site visit but they will largely be based in an office on the mainland. Engineer =/= mechanic/technician). Most major universities and industrial research labs are located in and around cities - some may be in smaller cities (such as Cambridge) as part of a university campus on the outside of the city due to the space requirements, but you aren't in the wilderness. There are of course major universities in even busy metropolitan cities like London - Imperial, UCL, KCL etc all have major research undertakings in various STEM areas.
Moreover, "lab work" in the sense of what a professional, appropriately qualified scientist does is nothing like labs as you will have experienced them. You are not simply performing meaningless procedures that a trained monkey could do, you are actively designing and planning experimental inquiry, then documenting and as applicable publishing this. It's completely different - again, working as a scientist in a lab is not the same as being a lab technician/assistant. Additionally you will spend varying amounts of time out of a formal lab in any case - depending on exactly the nature of your work. At a university as an academic, you will inevitably have some teaching responsibilities unless you are fortunate enough to get a major fellowship allowing you to cease such activity. Both in industry and in academia you will spend at least some time out of the lab and in offices, writing papers/reports/similar, having meetings with management etc, and analysing the results of the lab work.