First car advice

Hi, I was hoping someone on here could give me some advice/leads on what cars would be suitable to my needs.

So, a bit of background. I'm 24 and am yet to obtain my driving license, as it was previously unnecessary and unaffordable for me. However, I recently got a new job which involves a lot of travelling around the country, so driving would make my life a lot easier. Therefore I'm looking to pass my test and buy a car asap.

I would need a car that is comfortable and reliable on long distances, with good fuel economy. As a young/new driver, the typical choice of car for people in my job (such as a BMW 3 series) would cost me an arm and a leg on insurance. Any general advice on cheaper suitable alternatives?

Thanks in advance