Managed to get the tomatoes into jars after cleaning the kitchen, the jars and pots and anything else I thought I might be using. Did the hot water and cold water thing to get the skins off and then put them into jars. Got way more than I thought and ended up washing another large jar quickly to put the last of them into. Had no lemons left at that stage so added some vinegar instead. Will use that one first I think.
So, total of six kilos of tomatoes gave me 3 x 1 litre and 5 x .5 litre jars. Of course they wouldn't all fit in the canner so I had to put one of the smaller jars on top of the others. Same height as the the larger ones so hopefully it'll be okay.
I didn't de-seed the tomatoes as they were very fleshy to begin with but they ended up much juicier than I thought at the beginning. Oh well, it's all a learning curve I suppose. And my 2-ring hotplate is underperforming as spectacularly as I feared. I put them in there at just after seven o'clock and it took nearly two hours to boil (I had added a couple of kettles of boiling water, not just cold) and has boiled a little bit on and off since but never really properly. Temp hasn't gotten above 85 degrees either. But they've been in for nearly three and a half hours now and I'm tired and want to go to sleep so I'm taking them out. To hell with it. At the very least I'll find out in the morning if my first attempt at water bath canning worked at all. I suspect it won't with at least one of the leifheit jars as I was left with a spare ring but no lid at the end. I caught one instance where two lids were stuck together before I used them but obviously must have missed one before that. Too tired to care though.
Here's a pic of the hotplate. The small pot had the lids in it, when they had boiled for 10 minutes I moved it on top of the oven, which had the jars in it and gets very hot on top as well. The red pot is a 13 litre stockpot which I heated water in to blanch the tomatoes in. And you can see the size of the water bath canner beside that. I think that having both rings on on the hotplate seems to actually detract from the amount of power each gets so I have the canner on the larger ring with just a bit of it on the smaller one and had the smaller ring on just for a short while.