Apple Airport Extreme to boost signal or go for ethernet cables?

My internet is far from perfect and there's always multiple points in the day when the router will need resetting in an effort to boost signal, sometimes it works, sometimes it doesn't and we're all left frustrated with out slow connection but more so for me as i'm always the furthest away from the router while everyone else is usually in the room next to it. Anyway it's been really bad lately and i'll be calling my internet provider tomorrow to complain and i won't be taking any of that 'have you tried turning it off and on again' bull off them this time. In any event, whether they send someone out to tinker with it or not, i want a faster connection. So i'd like to know a little bit about my options as i see them, one is to go old school and get a long ethernet cable and run it along the ceiling and along the stairs to my room where it can be connected to a hub and then to other devices. Not a wireless option so not one i'm keen on but being wired it will be reliable and faster at least when i'm at my desk, i don't particularly want to drag a cable around with my Mac, one is enough (power cable).

So the other option i had thought of was looking at getting an Apple airport express but i would like a question or two answered before i do and i don't think the guys at my local storm front store (an Apple licensed dealer here in the UK) will be able to answer me directly, trust me. I want to know if it can be used to boost wireless signal alongside my router or would i have to use it as my primary router? What i'm hoping is that i could plug it into my router via an ethernet cable, run that cable up to my room and run the device there so i can get great signal in my room and anywhere else upstairs. If this can be done, then i'll buy one, if not but it can boost signal over my current router then again i think i'll buy one depending on how easy it is to set up since it would be taking over from my current the current router from my internet provider? W

So worst case scenario i'd just end up running a ethernet cable upstairs from that while having better signal downstairs lol Just to add, i live in a large house that was built in the mid 50s/early 60s so the electrics are quite old so expect that contributes to the poor internet and the fact that we can't use three large appliances at once else we get a power cut lol fml. If someone could elaborate on these scenarios for me that would be most appreciated, i'd like to pick one up asap but depending on how much i can benefit from it.