Tbh, local advertising won't cut it for an online niche(ish) company, and you will have to pay a bit for any advertising that will work.
Have you thought about printing some cheap leaflets in large quantities and dominate a particular area with them. Thats the cheapest method of advertising I know. Also if you are looking for cheap leaflet printing try London Print Shop http://www.londonprintshop.com
Unfortunately it's typical for brand development to be a money loser when first exposing the public to it, companies with lots of operating capitol are of course in a better position absorb those initial promotional costs.
One free possibility is to write a press release, with the hops that your announcement would be picked up by a news reporter with no time to do their own research (I don't know if they are equally common in the UK) typically a factual announcement with perhaps some human interest twist to make it press worthy. There are free and paid press release distribution services.
A few top rated examples (there are dozens of press release sites)
npr.org
highwire.stanford.edu
aip.org
prweb.com (well known paid distributor starting at $89)
programmersheaven.com
prnewswire.co.uk
prnewswire.com
newswire.ca
newslink.org
marketwire.com
internetworldstats.com
freepress.net
Google Adwords previously mentioned is one of the best known paid ad systems, it's far from the cheapest but it's ads are quite effective at bring qualified prospects, usually to a web site. These ads can be geo targeted to only reach people within driving rang of your location.
If you created a free Facebook page with some entertaining/informative information in audition to the product info, you might attract a few free visitors, after getting about 30 likes you can give the page a cleaner name and log onto facebook using the company name, which makes a link to your page every time you comment on another page or in a group, you could use their paid ads to send demographically targeted prospects, like only females 18-30, living near who perhaps mention children as one of their 'interests'
These are both self-serve ad systems that just require a credit card, you can find first time user only vouchers for $30 to $100 used to entice people to give them a try.
When one sets up a 'store' on Amazon.com they help in getting viewers of your product as part of their fees, I believe you pay primarily a percentage of the sale.
You have to post solo ads. Type in google keywords such a baby clothes+newsletter+ezine. Also find blogs that colect leads and than contact those blog owners and ask them to buy a "solo ad" to there list. Wery wery awesome, they're most rapid buyers!
I have my own baby clothes site and I need to advertise more. I have made use of free advertisement like Gumtree & Free ads ect. I have recently printed some leaflets so I can post them about for free as well.
I am also currently looking at advertising with netmums.com as its the cheapest ad going. But nothing has really given me a boost in sales!
Is there anywhere else/anything else I can do..
We are a UK based company and ship within UK only