Our home is a bungalow (sort of) which is based on two 17th century cottages merged together under a single roof with extensions. The walls of the original cottages are mainly flint, which is opaque to microwave frequencies so getting wifi coverage in some areas (like the daughters' bedrooms) was difficult.
But it was completely solved using a mains Powerline network. I use cheap TP-Link 300Mbps devices (you can even get them in Sainsburys). One unit is plugged into a wall socket and connected to the router using an ethernet cable I then have separate wireless adapters in both of the girls' rooms, and a wired one in the dining room (that's been there for a month because SWMBO is currently using it as her office). Each unit just plugs into a mains socket and creates a local wifi access point (with its own SSID and key) filling the bedroom or an ethernet socket that is just plugged in when needed. The original two have run without missing a beat for several years, and the LAN speed varies between 100 and 190Mbps at each node (it's never clear why - my theory is that it's actual routing/switching functionality is a bit crude), but as I only get 12Mbps broadband (WAN) speed I'm not that bothered.
These units work very well PROVIDED YOU FOLLOW THE INSTRUCTIONS. You must plug them directly into wall sockets - not extension leads of any kind, because the twisted wire flex of the extension lead seriously chokes the signal - plugging it into a 2-foot extension lead to a 4-way mains adaptor knocked the speed of the network back to under 1Mbps. Using an almost identical block on a 1.5m lead it wouldn't work at all. So plug it directly into the wall socket (and make sure it isn't one of those special wall sockets with "surge protectors"). If you can't spare the socket. Plug the main unit straight into your router with a piece of decent cat 5e or Cat 6 ethernet cable. For the wireless access points at the other end, set them up with unique SSID names - NOT THE SAME NAME AS YOUR ROUTER! I've seen people get very confused about this - you're not extending the existing wifi, you're adding additional wifi networks.So they need separate names (you c an use whatever key/password you like). I use a cheap one and it's perfectly reliable.
Finally - we have a summer house 80 yards down the garden which has power - a buried armoured cable with large, solid conductors. If I plug one of the powerline units into a socket in the summer house I can get well over 60Mbps wifi over most of the garden (thin wooden walls!)
€0.000003 supplied,
PDR