Trouble with white welchs wine brew

I'm making wine with welchs grape juice and a bit of fresh apple juice. It has been 12 days and there is no sign of activity in the air lock. The temperature in the house is quite cold, falling at night to about 14 degrees celsius and 17 during the day. The balling on the hydrometer is 29 and two packs of yeast went in. I suspect that there is no activity because it is too cold or perhaps I've put too much sugar in. What could be the problem?

You're right on both accounts. At balling of 29 (AKA 1.120) makes for very slow fermentation starts and your temperatures are below what most wine yeasts can handle.

So do you think it will just take longer than normal?

I don't see how Welch's grape juice plus apple juice could give you an OG of 1.120, you might want to verify. The apple juice should LOWER the OG, not raise it.

There might also be enough stabilisers and inhibitors in the grape juice that fermentation will not occur no matter what you do.

Raise the temparature to 18-22 degrees and see what happens.