Hi Kat
I read through your other thread and I imagine you are totally bewildered by all the well meant responses.
In my opinion with electric bikes as a rule of thumb you do get what you pay for, and when on a very tight budget there will always be considerable compromises to be made regarding quality of components, ease of use, range and quality of battery etc.
If your budget is low I think you could do a lot worse than the Halfords deal.
You'll get a bike that will help you get out with the rest of the family.
It may not have a huge range and may not be the best hill climber out there.
But at least you can afford it. For the £250 you have left in your budget you could choose to buy a second battery in due course, if you feel comfortable with the bike, and need to go further.
Halfords may not be everyone's choice, but at least you'll have somewhere local to take it back to if you have problems, and a warranty if you need it.
If I were you, I'd ask them to let you try it out, and if it feels OK for you, go for it.
£500 is pretty cheap for an ebike purchased from a major high street retailer.
Just my two penn'orth.