You can either buy a 3rd party router, a mesh kit or a booster/Pod for £5 a month from Virgin. For Mesh kits most people have been recommending the https://www.tp-link.com/uk/home-networking/deco/deco-m3/ however I've never used it to be able to say how good it is but other community members seem to hold it to some form of high regard, in terms of routers the only thing I would really say is look at TP-Link, ASUS or Netgear as those 3 are fairly recommended and reliable, I myself have a Netgear r7800 Nighthawk which is fairly old but still seems to be handling WiFi coverage without issues.
** I work for VirginMedia but all opinions posted here are my own.
if by booster you mean the new pod then yes they help but they will cost you £5 a month for ever or as long as you stay with VM - if and when you leave they will not work with any other system - i assume you would have to send them back
so do the maths £5 a month against an outlay for something that you keep and can use with any other isp
mesh systems are the new tech - many and varied at different price points - simple to set up and they work - choice is yours from £100 ish to a few hundred - not recommending but have just fitted a Netgear Orbi - certainly not the cheapest but am 100% impressed
VM now offer "wifi pods" rather than the old boosters. The pods are better, but not as good as a standalone mesh wireless system (I'm using a TP-LInk Deco M4, that's been first class). If you get the pods free with your package they're well worth a try, although there's been some supply chain issues, and you might have to wait a few weeks to get them.
If you pay to rent them, then you'd have to be bad at maths, because the £5 a month for a single pod means that in eighteen months you'd have spent the same as buying outright a superior three-unit mesh system. As a guide any TP-Link or Tenda Nova mesh system is good value and effective for around £90-130, but make sure you avoid the cheapo units such as the TP-Link Deco E4 or or Tenda Nova MW3, because those are hobbled by a slow 100 Mbps connection between the hub and the mesh system. Unless that is, you're on a 100 Mbps contract and firmly have no plans to upgrade in future, in which case they can be a bargain.
To throw another option in the mix, the last few years I've been using the ASUS AC86U (downstairs) with my old AC68U as a mesh node via wireless backhaul (upstairs). The AC86U is essentially the ASUS equivalent of Netgear's R7800 that was mentioned earlier. Both have a good reputation from what I've seen.
We're on the 200/20 service and I can max out the connection on the 5 GHz band with the AC86U, so if you go for a new router, I would look at ones that are at least the spec of the AC86U, or higher. It's also worth noting, there are many factors that influence the performance between a router and its client devices.