Yeah, you really SHOULD make a starter.. However.. I will say this. I have made this beer without a starter and it was fine. I used 1968 London ESB as well.. Keep the temps in check, and once it looks like it's dying down, make sure to swirl it a bit and allow it to warm to room temp. It will flocc out very well, so keep that in mind. If you choose to not do the starter, be sure to use some yeast nutrient if possible, and get plenty of O2 into it. The fresher the pack, the better. When I did it, my pack was inside 2 weeks old. It's not too late to make a starter. If I'm brewing Saturday, usually pitch that afternoon/evening anyways, and I can make it Friday afternoon, let it go all night, and it's usually done in the morning. I can put it in the fridge and it'll settle out fast. You'd need some DME, or even LME if you have it though.