No, absolutely no need, and very expensive for a proper ehu, see if you really like camping first.
just make sure you have plenty of warm bedding, layers under you as well as over. A picnic blanket on top of your airbed, and a hotwater bottle, warm clothes , and you'll be fine .
I have camped for years and never felt the need for EHU
some people need the extra luxury that That EHU provides but some can manage without, it depends really on your needs and what you expect from your trip
EHU is useful for the kettle, lights, fan heater & charging the batteries for the phone & camera. It is expensive to get all the bits & pieces & not essential. Try camping a few times to see if you like it first. The weatther isn't that cold at the moment.
As Oldham says if you haven't booked a pitch with EHU, then its pointless. A proper EHU will cost between £40-£60 depending on what deals are on in various shops at the moment and that's a lot of money. You don't need it at this stage. Go away for the weekend and see if you and the gf enjoy it - if you both do you will probably decide the money is better spent on getting better/warmer sleeping bags etc to replace your Argos ones.
Try the whole experience out first and then you can start to decide what your priorities are when you get back.
I really feel the cold quite badly due to a medical condition so I knew I would never enjoy camping if I was cold. I also hate feeling "pinned down" so lots of layers wasn't really an option for me so we bought EHU from the start.
Absolutely love camping but I need my EHU like others need their alcohol!!!!!
For us, running a fridge, having safe lighting and having the option of a fan heater are essential. (Fan heater comes in very handy for drying out wet stuff as well as keeping the chill bearable on cold nights.)
Not interested in "back to nature" stuff thanks. Not with 2 kids anyway.
We toured round Europe last summer with no EHU - no problem!
The stove and fridge both run off gas - everything else was battery powered (e.g UFO lights which go on for ever!).
The only things that needed electric were our phones and occasionally recharging the laptop - the phones recharged from 12v lighter adapter in the car and we had an inverter in the car for the laptop (but could probably have found a 12v for that too if we'd bothered).