Tell him to have a look at the GetVoting website. Whilst he doesn't have to take its advice (it tells you who to tactically vote for to remove Tories), they do have up to date polling for each constituency, so he can decide what might be for the best. Hopefully for him the tactical voting recommendation is Lib Dem!
GetVoting
I’ve just had a look at the Getvoting website and found it quite interesting.
I‘ve always been a centre right Conservative voter, but at the last election in 2019 I voted Lib Dem because as I didn’t agree with Brexit there was no way that I could vote for Boris. During these last 5 years I have just got to the point where I want the Conservatives out and I say that as someone who has been voting Conservative since the late 1970’s.
Where I have live the current MP is Conservative, as it generally is, and he had a majority of just over 16,000 over Labour in 2019. The Lib Dems have never done anything here and didn‘t even quite manage to get 3,000 votes in 2019.
In the 2019 election the share of the votes here was Conservative 60.8%, Labour 30.1%, Lib Dem 5.5% and Green 2.3%.
Getvoting are predicting for the forthcoming election Conservative 27.2%, Labour 45.1%, Lib Dem 4.3%, Green 4.2% and Reform 17.7%.
To vote tactically it is suggested to vote Labour.
If it was looking very close I would perhaps have considered tactically voting Labour just to get the Conservatives out. However, as it’s looking like a comfortable Labour majority here, I am thinking very seriously of voting Lib Dem again, even though here it could be seen as a wasted vote.