I have been exploring my family tree online for about 18 months and, yes, it is time-consuming but for some of us it is also riveting. However, it can prove quite expensive too. I have a long way to go because I have been unable to verify certain people - sometimes they just disappear off the censuses! There are some helpful free sites and most of the subscription sites offer the opportunity of a free trial for a period and to pay for credits as you go (in other words you buy so many credits which gives you a set amount of access to records) so it is as well to know who you specifically wish to pursue when you buy these. If you jump around, the desire to keep buying credits is infectious and you run up bills! It is then worth assessing the cost of membership to a site providing unlimited access for a year such as Find My Past. To start I would recommend a site like Genes Reunited which costs under £10 for six months' membership and allows you to build your tree, have access to other members safely and other facilities. It is interesting when you do get a relative match and can help each other. I've been in touch with members from the UK, Australia, New Zealand, USA and Canada as well as Europe. Be aware that not all the surprises are happy ones and don't make the mistake of assuming that a find with the same name is necessarily your ancestor! Some people have spent hours researching what turned out to be a family tree belonging to someone else!
I would encourage you to give it a try and see if you like it!