Cheap train Glasgow to London

[ssd]

I'm trying to get me and dh a return to London in a couple of weeks, we don't have a railcard but I'd probably get the 2 together one. That's £30. I've been trying to figure out what days and times are cheapest. We'd probably stay in an airbnb for 2 nights. I'm really trying to find the best deal. I don't want to go by bus, i have nightmares of this when i was younger. We have driven before but it takes ages...

Can anyone give me advice of what days or times might be cheaper to go, we can go on any day.

Thanks

If you want to use Avanti West Coast (not recommended but sometimes you need to!) I find they often have cheaper tickets leaving Glasgow after about 11am, and again later in the day (the trains that get into London about 9pm onwards), mid-week (ie Tues/Weds/Thurs).
I've travelled back on Saturdays a few times, which won't work over the next few weeks (due to strike action) and if you do that during football season, try to avoid post-match times....

You should be covered for delays as long as the purchase time for your origin-GC train shows you could have had enough time to get there.

I've missed my advance ticket train from Glasgow to London before when there were delays and cancellations from my nearest station to Central, and their ticket office (I can't remember if this was in early Avanti days or late Virgin) gave me that little waiver to show I was entitled free on the next train.

It's treated as one journey. In the same way, if your Glasgow-London train is delayed significantly and you're claiming Delay Repay, you can also claim for the first leg of the journey as part of the same journey. (Splitting this onto separate tickets is also useful, because with Delay Repay, if you have an A-B train that's 3 hours delayed but you had a B-C train with a 3.5 hour planned wait, so you still make it, you'd get nothing for the A-B train if you have a through ticket but the whole of the A-B train price if you have split tickets for that part of the route, even though your time on the train is just as wasted and their service just as bad.)