Can / Will British Gas Engineer fit a self supplied item

[catflap]

Unless you have a sludge contamination problem there is not much benefit in fitting one. If you end up with a Magnaclean it has every chance of being the single most unreliable part of the system, ironically.

Hydropath is total DIY, no one gets wet, and it has a plug on it.

Don't think we have a sludge problem but the system has been running for 20 years with it only having been drained once in that time to fit some more radiators. With a brand new tank going in I thought it might be worth fitting a Magnabooster now or should we just wait until the boiler eventually needs replacing (kettles a lot now so that might not be too long).