Firstly congratulations on setting up a new business especially at the same time as getting a divorce - you must have incredible strength.
I read your post last night and obviously misread as to the scale of your business but here's my tuppence worth anyway as little acorns etc.
I looked into doing something similar last year but quite quickly down the line we realised it wasn't our passion. However I did get some good information from moneymagpie.com about selling cards through ebay as they have a facility for online shops and other auction sites might do similar things. My personal
opinion is that money magpie is useful but not 100% ethical in its links so be careful.
To get the word out in addition to those you've mentioned, consider asking your children's school if you could have a stall at the Christmas fair in return for a donation/small percentage of sales. Brownies, guides, cubs, local churches also are coming up to Christmas fete time and putting your web address on the back gives someone a chance to come back to you. Most towns/counties also have charity shops that are specific to that area so they might be willing to do a similar thing or you could even do a special edition print just for them. I know some of these ideas may reduce your profit but at least you would also be helping a good cause.
The other thing to consider is legal advice - I have heard many stories of friends setting up in business with no form of contract which was fine until either the stakes got higher or one of them wanted to pull out. Plus of course there's our friends at www.hmrc.gov.uk
(the tax office!). When I first set up as an employer they were really helpful and I got quite a bit of free advice. I still mess up from time to time as I do my own tax returns but as long as you keep communicating with them and your local office in particular, they will help you through.
Hope your son gets better soon. If it's a recurring thing rather than food poisoning then look into food allergies as it's often overlooked by GP's and consultants. My ex's asthma used to get worse after drinking wine due to the sulphur dioxide. There is a simple blood test that can be arranged through the surgery and you can also get a local anaesthetic cream for him (ask the GP for 'magic cream' he/she will know what you're talking about!)
Best of luck with everything.