Welcome to the forum Kev,
Is it easier/cheaper to replace the whole wish bone rather than try to replace bushes?
You will need to remove the wishbone to get the bushes out, so you may as well replace the wishbone and the bushes at the same time. Although not the cheapest for parts, its much easier and quicker, so could end up cheaper in the long run.
The other advantage of changing the whole lower arm and bushes is that if you are unsure if its the bushes OR the arm, changing both removes the question.
You can find
the lower arm assembly complete with bushes and ball-joint here which could easily work out quicker and therefore cheaper and less hassle than doing the bushes yourself. Some of those kits even come with the drop-link tie-bars too.

- Lower control arm or lower wishbone for a Citroen C3 suspension
a picture of the lower arm from a C3 available from
Euro Car Parts - free delivery available 
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Something can be said for changing suspension parts in pairs (left and right), but I won't say it
Getting those lower control arm bolts out can be difficult as the torx head doesn't have a very deep socket and the threads are often corroded. It can take time to get them out and some resort to cutting and grinding and others have welded some assistance to the head (see picture)

- Remove the lower control arm bolts on a Citroen C3