Thank you very much!

May 6th is a bank holiday so the trains will be quieter. However, and not a full strike day, there is an overtime ban by some train drivers on the National Rail services - not the underground.

Are you staying near Waterloo station or travelling there by train, if so from where please?

You'll be able to get on a train but may have to let the first few leave without you first. The Northern line will likely be much busier, so the Bakerloo then Victoria line option is probably the one to go for. You'll find most passengers will leave the train at Oxford Circus anyway, so you may have an easier time boarding the Victoria line train.

Changing from the Bakerloo to the Victoria line at Oxford Circus is indeed the right option to choose - the platforms are parallel to each other there, separated by tunnels. It’s literally 20 metres or so walk between them.

You will need to be able to wrangle your luggage up and down short flights of stairs, just enough to get you to and from the walkways above the tube tunnels. Other than that, it’s mostly escalators. Even with luggage, if at all possible obey the “stand on the right” principle so have your luggage on the step behind or in front of you.

Thanks - good to know that was the right choice. Our bags are not too big, so managing them on the stairs should be fine. It appears the walk from victoria line kings cross to lner kings cross is more like 7 minutes, but I will allow time for that,

There won't be a proper rush hour on the Bank Holiday.

#6 - it’s true that getting from Kings X/ St Pancras tube platforms to the main rail lines can seem like it’s taking ages, though 7 mins is probably about right. It’s two big rail stations served by one tube station that itself serves four separate pairs of tube train platforms, so there are a lot of permutations.

All three have been renovated and remodernised relatively recently, though, so they are now set up to cope with the load. I’d be generous with your time allowance - if you are there early Kings Cross is not a bad place to stop for a coffee.

The Bakerloo and Northern lines are two of the worst tubes lines. But you won’t be on it long, and if you have to squash and push on, just treat it as a genuine London experience. There may be some huffing or tutting from other passengers, but that’s ok too. Or you may be lucky and it’s not a busy train at all.

Whichever, I’d allow a good amount of time for navigating your way through unfamiliar stations.

I'd be looking to be on the Bakerlooline platform at Waterloo by 0800 or so. I don't like rushing but I don't expect it will be crazy busy on a holiday.