is this a good meal plan

breakfast: cornflakes with semi skimieed milk and a cup of tea

snack:ceralbar like rice krispie

lunch:lemon curd sandwichs with a bag of wotsits crisp

sometimes a afternoon snack which would be 1 biscuit like a ginger nut

dinner: chicken nuggets with 1 waffel and baked beans and either jelly pot or jam tart fpr dessert

sometimes i have a snack before i go bed which would be 1 biscuit

also i suffer from acid reflux

I suggest you have a look at the 'what did you eat today' as this doesn't look like enough for a weight loss plan, let alone weight gain.

You see what happens to your corn flakes once you poor the milk on and let it sit for a few minutes?  That's exactly what happens in your stomach.  If you want something more substantial, I would switch cereals.  Ditto for your Rice Krispie square.  At the very least, add some All Bran Buds to your cereal.

this is not a substantial gaining meal plan whatsoever....i would change it to add the following if you wanted to eat what you have planned

breakfast: cornflakes with semi skimieed milk and a cup of tea [change the tea to a cup of juice or milk, add nuts to your cornflakes, have a hard boiled egg or a yogurt as well]

snack:ceralbar like rice krispie [add a string cheese, yogurt, cottage cheese, or trail mix to your snack]

lunch:lemon curd sandwichs with a bag of wotsits crisp [have the precise number of sandwiches that are planned, have dip or cheese with your wotsits, have a juice or cup of creamy soup as well]

sometimes a afternoon snack which would be 1 biscuit like a ginger nut [1 biscuit is not enough...have about 2 biscuits, a glass of milk, and some peanut butter]

dinner: chicken nuggets with 1 waffel and baked beans and either jelly pot or jam tart fpr dessert [how many nuggets? at least 6-10, put something on your waffel, and have some cheese on your baked beans]

 sometimes i have a snack before i go bed which would be 1 biscuit--add some ice cream or something to your snack

You just need to BOOST EVERYTHING--you are not getting enough calories with the way things are and you need to be more concrete with what you're planning

At first glance it looks like you're low on fat and protein, but I could be wrong. Make sure you are logging your food so you know how many calories you are eating. NEVER starve yourself. It may work at first, but then it will stop working and you will only end up hurting your body. Aim for a balanced 40% carbs / 30% protein / 30% fat diet. 

Log what you're going to eat for the day the night before so you know you're at what you should be. If you find yourself high on carbs and low on fat, for example, add some healthy nuts like almonds or walnuts, or natural peanut butter (made w/o hydrogenated oils).