Sometimes cheapest can be a false economy.
In 5GHz, especially.
When I first looked, I discovered that the cheapest wifi provision was limited to power levels suitable for America, not the ones allowed in the EU or the UK.
Likewise, the cheapest hardware didn't bother with the radar detection functionality, so limited the choice of channels to the "easiest" first 4 (channels 36, 40, 44 and 48).
When you're given shoddy hardware, it is no wonder people think that 5GHz isn't as good as 2.4GHz. IMO it is better.
In reality, there are 4 more channels (52, 56, 60 and 64) that can use the same power as the first four. Then there are 11 more channels that can use a much higher power setting ... if the hardware can cope.
Once I discovered this, I stopped relying on the ISP's router/modem as a WiFi access point, and installed my own standalone version, looking at the products that are nearer enterprise offerings.
What channels are you given a choice of by BT's and TT's hardware?