I tried the Hollybush lane route on my hybrid, what a disaster that way is, moon craters all the way down, then left down the path along the lake security fence leading back to the BWV path is s terrible surface littered with glass (so much so it looks almost deliberate). If you like fixing punctures I can recommend it. It’s almost better to carry on down Hollybush lane and over the roundabout at the end.
The other way that was mentioned is via Ramilles park and over the A331 footbridge (and the dreaded Hollybush lane) to rejoin the BWV via Hollybush Hill, the old tip which is now a nature reserve. The terrain on Hollybush Hill is grass and a bit rough here but it’s a very short distance. The rest is good quality paths or trails. Here is the route: Farnborough to Guildford via Tongham
Another posted mentioned the cut through the woods between 2 houses via a path that abruptly ends and turns into a nondescript grass track. This is found on my route after 5.1 miles. I didn’t fancy that and went the longer way round but with a much better track surface suiting my hybrid. I rode this today and it’s all good.