If you and your DH both have a free day at the weekend why not make that day your 'home ed day'?
You can join the local wildlife trust (I got a letter from ours yesterday saying they are doing free guided walks for new members) and they do loads of free or very cheap events.
We got frogspawn from freecycle last year (someone had mountains of the stuff - must have very amorous frogs in their garden) and we put it in shallow containers in the garden and the kids checked it every night and watched them changing from spawn to tads to little frogs. DD2 was in charge of making sure the water level didn't drop too much. It's something you can still do at home.
There is a lot you can do at weekends and if you gave up the foreign holiday then you could do even more each week. We don't go abroad but we do go camping for a week and it means we have a bit extra for day trips out and a lot of what we do is free.
I couldn't home educate in a month of sundays. Yes, I'm enjoying having my DC home for the two weeks holidays but by a week on monday I'll be desperate to get them back to school so I can tidy the house properly and have a bit of peace and quiet!
We've been away for a couple of days and got back late last night. We only went to Ipswich for teens university interview but we had fun, saw a new place, went swimming, ate out and then dropped in to see family on the way home. We are knackered today but if we were doing things like that all the time, I'm not sure it would be special. As it is, we will remember this because it was out of the ordinary.
If your DC were at home doing all these things every day, it would be normal. It wouldn't be something special they remember. We went den building once on Brownsea Island and my DC still talk about it, the fun they had, the peacocks which tried to nick our food and the way the boat took ages getting back because the tide was low. I think they would become very bored very quickly if this was an every day occurrence!