By that you mean use my current card until March 1st?
Sorry my post was badly worded.
It's going to cost you no more than £10 between now and 28th February to use your current BP Pulse Card. They might bill your next cycle, but they probably won't, so up until then it will be likely free.
From 1st March, you'll probably be better off getting a BP Pulse Membership at £7.85 per month via the BP Pulse App. Your first month's Membership is free, and then the following months you pay the £7.85 per month but they give you a £9 credit for the first five months, so you have the option for a charge if you need one.
This way, you'd keep your free charging at work with the BP Pulse network. I think that's correct anyway!
You also may as well get the elmoCharge Card with the £100 Credit on it, as it's free, and even if you use it once it's one free charge you've got.