It's customary for the proposer of a thread to give some indication as to what they think might happen, rather than simply ask for the opinions of others.
That's a graph of polling through the early 1980s. If we take out the Falklands Factor, we see the following:
Labour on a steady decline from pretty much the moment Foot was elected leader. He took a party approaching 50% in the polls at the start of 1981, and by the end of 1981, had turned it into a party polling at around 30%, where it pretty much remained. 30% is probably the bottom level of Labour support. This decline is independent of the Falklands, the economy, or indeed everything other than that Labour went straight for rock bottom and stayed there.
The Conservatives also have a decline, but start to pick up just prior to the Falklands War. If the Falklands War doesn't occur, then we can probably knock 5-10% points off the Conservative vote (my estimate - other numbers are available). That puts them in the high 30s/low 40s come 1983 (or 1984, the last date for when an election has to be called).
The SDP is the wild card. The boost from the Limehouse Declaration has faded, and the numbers were falling even prior to the Falklands. But they appear to have stabilised at around mid 30s, before being hammered by the Falklands Factor.
Ignoring all else, and assuming nothing comes along to upset the apple cart, that's giving us roughly: Tory - 37-39%, SDP 34-36%, Labour 29-31% (give or take).
Because of the way the electoral system works under FPTP, that gives a rather distorted view. Labour and Tory votes tend to be concentrated, while the SDP votes were more evenly distributed. That gives the SDP a lot of second places to Labour and Tory in large parts of the country. OTL, we had Tory: 397, Labour 209, and Lib-SDP 23 (21 other). We can probably pull Tory down by around 50 seats, and distribute them 30 to Lib-SDP, 10 to Other, and 10 to Labour. Giving us:
Tory: 357.
Labour 219.
Lib-SDP: 53
Other 31
Other outcomes are possible.
That gives the Tories a majority of 54 - a solid working majority. The Lib-SDP are on a bounce, and looking to make a breakthrough. The Labour party will, as it always does, turn on itself with the different factions fighting against the Real Enemy - themselves.